When a famous or influential person tweets a link to a website, causing the site to crash because of the massive flow of internet traffic that insues.
Usually this will only happen to websites that don't recieve a substantial amount of traffic, since their servers aren't ready for hundreds upon thousands of visitors coming to their site.
Why can't I click on this link that this actor just sent out? I guess we must have Twitter crashed the site.
I didn't even know I could Twitter crash my own website! I guess I have a lot of followers!